The scheme, which has been launched with the St John Ambulance, is part of a response to a rise in acid attacks and terror incidents in London, and seeks to take advantage of the network of drivers across the capital.

Chris Phillips, former head of the National Counter Terrorism Security Office, said: "Threats to the nation's capital are changing at an unprecedented pace. You can pretty much guarantee that whatever incident happens in London, a black cab will be at the scene or nearby. Professionalising their response is a brilliant way to help keep Londoners safe."

Mytaxi conducted a survey of more than 1,300 drivers and found they are increasingly supporting emergency service employees in dangerous situations.

Over half of the respondents said they were hired as an alternative to an ambulance and 71 per cent said they had made emergency trips to hospitals for passengers with medical issues.